An entirely automated method to score DSS-induced colitis in mice by digital image analysis of pathology slides

Long-Term Triclocarban Exposure Induced Enterotoxicity by Triggering Intestinal AhR-Mediated Inflammation and Disrupting Microbial Community in Mice

Exposure to triclocarban (TCC), a commonly used antibacterial agent, has been shown to induce significant intestine injuries and colonic inflammation in mice. However, the detailed mechanisms by which TCC exposure triggered enterotoxicity remain largely unclear. Herein, intestinal toxicity effects of long-term and chronic TCC exposure were investigated using a combination of histopathological assessments, metagenomics, targeted metabolomics, and biological assays. Mechanically, TCC exposure caused induction of intestinal aryl hydrocarbon receptor (AhR) and its transcriptional target cytochrome P4501A1 (Cyp1a1) leading to dysfunction of the gut barrier and disruption of the gut microbial community. A large number of lipopolysaccharides (LPS) are released from the gut lumen into blood circulation owing to the markedly increased permeability and gut leakage. Consequently, toll-like receptor-4 (TLR4) and NF-κB signaling pathways were activated by high levels of LPS. Simultaneously, classic macrophage phenotypes were switched by TCC, shown with marked upregulation of macrophage M1 and downregulation of macrophage M2 that was accompanied by striking upregulation of proinflammatory factors such as Il-1β, Il-6, Il-17, and Tnf-α in the intestinal lamina propria. These findings provide new evidence for the TCC-induced enterotoxicity.

Quantitative Image Analysis for Tissue Biomarker Use: A White Paper From the Digital Pathology Association

Tissue biomarkers have been of increasing utility for scientific research, diagnosing disease, and treatment response prediction. There has been a steady shift away from qualitative assessment toward providing more quantitative scores for these biomarkers. The application of quantitative image analysis has thus become an indispensable tool for in-depth tissue biomarker interrogation in these contexts. This white paper reviews current technologies being employed for quantitative image analysis, their application and pitfalls, regulatory framework demands, and guidelines established for promoting their safe adoption in clinical practice.

Transpathology: molecular imaging-based pathology

Pathology is the medical specialty concerned with the study of the disease nature and causes, playing a key role in bridging basic researches and clinical medicine. In the course of development, pathology has significantly expanded our understanding of disease, and exerted enormous impact on the management of patients. However, challenges facing pathology, the inherent invasiveness of pathological practice and the persistent concerns on the sample representativeness, constitute its limitations. Molecular imaging is a noninvasive technique to visualize, characterize, and measure biological processes at the molecular level in living subjects. With the continuous development of equipment and probes, molecular imaging has enabled an increasingly precise evaluation of pathophysiological changes. A new pathophysiology visualization system based on molecular imaging is forming and shows the great potential to reform the pathological practice. Several improvements in "trans-," including trans-scale, transparency, and translation, would be driven by this new kind of pathological practice. Pathological changes could be evaluated in a trans-scale imaging mode; tissues could be transparentized to better present the underlying pathophysiological information; and the translational processes of basic research to the clinical practice would be better facilitated. Thus, transpathology would greatly facilitate in deciphering the pathophysiological events in a multiscale perspective, and supporting the precision medicine in the future.

Axolotls' and Mice's Oral-Maxillofacial Trephining Wounds Heal Differently

The Ambystoma maxicanum (axolotl) regenerates strikingly from wounds and amputations. Comparing its healing ability to non-regenerative species such as the mouse should help narrow in on mechanisms to improve human wound healing. Here, the tongue and intermandibular soft tissues of both mice (C57BL/6NCrl) and axolotls were wounded with a 2–2.5 mm punch biopsy. The study aimed to compare the differences between these 2 species following surgical resection with regard to the macroscopic and histological characteristics. These include wound closure times, epithelial wound sealing and thickness as well as acute immune marker myeloperoxidase (MPO) response over 30 days. Post surgery, mice visually showed greater haemorrhage; their wounds immediately collapsed while it took 14 days for the axolotls mandibular void to close. The epithelium sealed the axolotls’ wound margins within 24 h with a maximal mean thickness of 0.42 ± 0.13-fold normalized to unwounded skin. In mice, the epithelium separately sealed the ventral and dorsal sides, respectively at 7 and 7–30 days with mean maximal epithelial thicknesses reaching 13 ± 5.6 and 3.0 ± 0.63-fold. Mean MPO-positive cell values peaked in axolotls at 14 ± 1.5-fold between hours 6–12; while in mice, it peaked at 8.7 ± 0.9-fold between hours 24–96. We conclude that axolotls form smaller blood clots, have a faster and thinner epithelial cell migrating front, and a shorter MPO-positive cell response in comparison to mice. These observations may help refine future oral and facial wound-healing research and treatment.

Systematic Scoring Analysis for Intestinal Inflammation in a Murine Dextran Sodium Sulfate-Induced Colitis Model

Murine colitis models are tools that are extensively employed in studies focused on understanding the pathobiology of inflammatory intestinal disorders. However, robust standards for objective and reproducible quantification of disease severity remain to be defined. Most colitis analysis methods rely on limited histological scoring of small segments of intestine, leading to partial or biased analyses. Here, we combine high-resolution image acquisition and longitudinal analysis of the entire colon to quantify intestinal injury and ulceration in the dextran sodium sulfate (DSS) induced model of murine colitis. This protocol allows for the generation of objective and reproducible results without extensive user training. Here, we provide comprehensive details on sample preparation and image analysis using examples of data from DSS induced colitis. This method can be easily adapted to other models of murine colitis that have significant inflammation associated with mucosal injury. We demonstrate that the fraction of inflamed/injured and eroded/ulcerated mucosa relative to the complete length of the colon closely parallels clinical findings such as weight loss amid DSS-induced disease progression. This histological protocol provides a reliable time and cost-effective aid to standardize analyses of disease activity in an unbiased way in DSS colitis experiments.

Proof of Concept for a Deep Learning Algorithm for Identification and Quantification of Key Microscopic Features in the Murine Model of DSS-Induced Colitis

Inflammatory bowel disease (IBD) is a complex disease which leads to life-threatening complications and decreased quality of life. The dextran sulfate sodium (DSS) colitis model in mice is known for rapid screening of candidate compounds. Efficacy assessment in this model relies partly on microscopic semiquantitative scoring, which is time-consuming and subjective. We hypothesized that deep learning artificial intelligence (AI) could be used to identify acute inflammation in H&E-stained sections in a consistent and quantitative manner. Training sets were established using ×20 whole slide images of the entire colon. Supervised training of a Convolutional Neural Network (CNN) was performed using a commercial AI platform to detect the entire colon tissue, the muscle and mucosa layers, and 2 categories within the mucosa (normal and acute inflammation E1). The training sets included slides of naive, vehicle-DSS and cyclosporine A-DSS mice. The trained CNN was able to segment, with a high level of concordance, the different tissue compartments in the 3 groups of mice. The segmented areas were used to determine the ratio of E1-affected mucosa to total mucosa. This proof-of-concept work shows promise to increase efficiency and decrease variability of microscopic scoring of DSS colitis when screening candidate compounds for IBD.

Triclocarban exposure exaggerates colitis and colon tumorigenesis: roles of gut microbiota involved

Triclocarban (TCC) is a widely used antimicrobial ingredient in consumer products and is a ubiquitous contaminant in the environment. In 2016, the FDA removed TCC from over-the-counter handwashing products, but this compound is still approved for use in many other personal care products. A better understanding of its impact on human health could lead to significant impact for public health and regulatory policies. Here we show that exposure to low-dose TCC exaggerated the severity of colitis and exacerbated the development of colitis-associated colon tumorigenesis, via gut microbiota-dependent mechanisms. Exposure to TCC increased dextran sodium sulfate (DSS)- and interleukin 10 (IL-10) knockout-induced colitis, and exaggerated azoxymethane (AOM)/DSS-induced colon tumorigenesis in mice. Regarding the mechanisms, TCC exposure reduced the diversity and altered the composition of gut microbiota and failed to promote DSS-induced colitis in mice lacking the microbiota, supporting that the presence of the microbiota is critical for the pro-colitis effects of TCC. Together, these results support TCC could be a novel risk factor for colitis and colitis-associated colon cancer, and further regulatory policies on this compound could be needed.

Effects of Linoleic Acid-Rich Diet on Plasma Profiles of Eicosanoids and Development of Colitis in Il-10-/- Mice

Dietary intake of linoleic acid (LA, 18:2ω-6) has risen dramatically in recent decades. Previous studies have suggested a high intake of LA could increase tissue concentrations of proinflammatory and protumorigenic ω-6-series eicosanoid metabolites, increasing risks of inflammation and associated diseases. However, the effects of a LA-rich diet on in vivo profiles of eicosanoids and development of inflammatory diseases are understudied. Here, we treated spontaneous colitis-prone (Il-10^-/-) mice with a control diet (∼3 Cal% LA) or a LA-rich diet (∼9 Cal% LA) for 18 weeks and analyzed the effects of the LA-rich diet on profiles of eicosanoids and development of colitis. We found that treatment with the LA-rich diet increased the tissue level of LA: the liver levels of LA were 5.8 ± 0.6% in the control diet-treated mice versus 11.7 ± 0.7% in the LA-rich diet-treated mice (P < 0.01). The plasma concentrations of a series of LA-derived metabolites, including 9-hydroxyoctadecadienoic acid (HODE), 9,10-dihydroxyoctadecenoic acid (DiHOME), 12,13-DiHOME, and 13-HODE were significantly increased by treatment with the LA-rich diet (P < 0.05). However, the LA-rich diet had little effect on the severity of colitis in the treated Il-10^-/- mice. These results suggest a limited role of increased consumption of dietary LA on promoting colitis in the Il-10^-/- model.

Prescription Opioids induce Gut Dysbiosis and Exacerbate Colitis in a Murine Model of Inflammatory Bowel Disease

BACKGROUND AND AIMS

Opioids are the most prescribed analgesics for pain in inflammatory bowel diseases [IBD]; however, the consequences of opioid use on IBD severity are not well defined. This is the first study investigating consequences of hydromorphone in both dextran sodium sulphate [DSS]-induced colitis and spontaneous colitis (IL-10 knockout [IL-10-/-]) mouse models of IBD.

METHODS

To determine the consequences of opioids on IBD pathogenesis, wild-type [WT] mice were treated with clinically relevant doses of hydromorphone and colitis was induced via 3% DSS in drinking water for 5 days. In parallel we also determined the consequences of opioids in a spontaneous colitis model.

RESULTS

Hydromorphone and DSS independently induced barrier dysfunction, bacterial translocation, disruption of tight junction organisation and increased intestinal and systemic inflammation, which were exacerbated in mice receiving hydromorphone in combination with DSS. Hydromorphone + DSS-treated mice exhibited significant microbial dysbiosis. Predictive metagenomic analysis of the gut microbiota revealed high abundance in the bacterial communities associated with virulence, antibiotic resistance, toxin production, and inflammatory properties. Hydromorphone modulates tight junction organisation in a myosin light chain kinase [MLCK]-dependent manner. Treatment with MLCK inhibitor ML-7 ameliorates the detrimental effects of hydromorphone on DSS-induced colitis and thus decreases severity of IBD. Similarly, we demonstrated that hydromorphone treatment in IL-10-/- mice resulted in accelerated clinical manifestations of colitis compared with control mice.

CONCLUSIONS

Opioids used for pain management in IBD accelerate IBD progression by dysregulation of the gut microbiota, leading to expansion of pathogenic bacteria, translocation of bacteria, immune deregulation and sustained inflammation.

Recent updates on the basic mechanisms and pathogenesis of inflammatory bowel diseases in experimental animal models

The specific pathogenesis underlining inflammatory bowel disease (IBD) is very complicated, and it is further more difficult to clearly explain the pathophysiology of 2 major forms of IBD, Crohn’s disease (CD) and ulcerative colitis (UC), and both disorders affect individuals throughout life. Despite every extensive effort, the interplay among genetic factors, immunological factors, environmental factors and intestinal microbes is still completely unrevealed. Animal models are indispensable to find out mechanistic details that will facilitate better preclinical setting to target specific components involved in the pathogenesis of IBD. Based on many recent reports, dysbiosis of the commensal microbiota is implicated in the pathogenesis of several diseases, not only IBD but also colon cancer, obesity, psoriasis as well as allergic disorders, in both human and animal models. Advanced technologies including cell-specific and inducible knockout systems, which are recently employed to mouse IBD models, have further enhanced the ability of developing new therapeutic strategies for IBD. Furthermore, data from these mouse models highlight the critical involvement of dysregulated immune responses and impaired colonic epithelial defense system in the pathogenesis of IBD. In this review, we will explain from the history of animal models of IBD to the recent reports of the latest compounds, therapeutic strategies, and approaches tested on IBD animal models.

Differences in colonic crypt morphology of spontaneous and colitis-associated murine models via second harmonic generation imaging to quantify colon cancer development

Background

Colorectal cancer remains the second leading cause of cancer death in the United States, and increased risk in patients with ulcerative colitis (a subset of inflammatory bowel disease) has motivated studies into early markers of dysplasia. The development of clinically translatable multiphoton imaging systems has allowed for the potential of in vivo label-free imaging of epithelial crypt structures via autofluorescence and/or second harmonic generation (SHG). SHG has been used to investigate collagen structures in various types of cancer, though the changes that colorectal epithelial collagen structures undergo during tumor development, specifically colitis-associated tumors, have not been fully investigated.

Methods

This study used two murine models, using A/J mice, one for spontaneous carcinoma and one for colitis-associated carcinoma, to investigate and quantify SHG image features that could potentially inform future study designs of endoscopic multiphoton imaging systems. The spontaneous tumor model comprised a series of six weekly injections of azoxymethane (AOM model). The colitis-associated tumor model comprised a single injection of AOM, followed by cycles of drinking water with dissolved dextran sodium sulfate salt (AOM-DSS model). SHG images of freshly resected murine colon were acquired with a multiphoton imaging system, and image features, such as crypt size, shape and distribution, were quantified using an automated algorithm.

Results

The comparison of quantified features of crypt morphology demonstrated the ability of our quantitative image feature algorithms to detect differences between spontaneous (AOM model) and colitis-associated (AOM-DSS model) murine colorectal tissue specimens. There were statistically significant differences in the mean and standard deviation of nearest neighbor (distance between crypts) and circularity between the Control cohort, AOM and AOM-DSS cohorts. We also saw significance between AOM and AOM-DSS cohorts when calculating nearest neighbor in images acquired at fixed depths.

Conclusion

The results provide insight into the ability of SHG imaging to yield relevant data about the crypt microstructure in colorectal epithelium, specifically the potential to distinguish between spontaneous and colitis-associated murine models using quantification of crypt shape and distribution, informing future design of translational multiphoton imaging systems and protocols.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5639-8) contains supplementary material, which is available to authorized users.

Deciphering the immune microenvironment of a tissue by digital imaging and cognition network

Evidence has highlighted the importance of immune cells in various gut disorders. Both the quantification and localization of these cells are essential to the understanding of the complex mechanisms implicated in these pathologies. Even if quantification can be assessed (e.g., by flow cytometry), simultaneous cell localization and quantification of whole tissues remains technically challenging. Here, we describe the use of a computer learning-based algorithm created in the Tissue Studio interface that allows for a semi-automated, robust and rapid quantitative analysis of immunofluorescence staining on whole colon sections according to their distribution in different tissue areas. Indeed, this algorithm was validated to characterize gut immune microenvironment. Its application to the preclinical colon cancer APC^Min/+ mouse model is illustrated by the simultaneous counting of total leucocytes and T cell subpopulations, in the colonic mucosa, lymphoid follicles and tumors. Moreover, we quantify T cells in lymphoid follicles for which quantification is not possible with classical methods. Thus, this algorithm is a new and robust preclinical research tool, for investigating immune contexture exemplified by T cells but it is also applicable to other immune cells such as other myeloid and lymphoid populations or other cellular phenomenon along mouse gut.

Implementation of an automated inclusion system for the histological analysis of murine tissue samples: A feasibility study in DSS-induced chronic colitis

Animal models are powerful tools to expand our understanding of human diseases. Histopathological evaluation of murine experimental models is often required to support further research; thus, a more rigorous evaluation of murine histological samples is strongly advocated. Indeed, the overall quality of tissue sections is critical to draw reliable and accurate conclusions. As several methodological variables may reduce the reliability of the pathological analysis, a standardization of the procedural steps required for the processing of histological murine tissues is advisable. Here, we describe a method to standardize the technical procedure from the initial preparation to the paraffin embedding of murine samples. Specifically, we have implemented an automated inclusion system, that is, the SAKURA Tissue-Tek inclusion instrument, which is routinely used for paraffin inclusion of human samples, to process murine specimens of intestinal inflammation. Colitis severity was assessed in chronically Dextran Sodium Sulphate (DSS)–treated mice by cytofluorimetric analysis of colonic cellular infiltrates, expression of inflammatory genes and histopathological analysis of tissue samples, comparing manual and automated tissue preparation systems. We here conclude that implementation of this technique can significantly increase the quality and the reliability of histopathological examination of murine tissues.

The kinase TPL2 activates ERK and p38 signaling to promote neutrophilic inflammation

Tumor progression locus 2 (TPL2; also known as MAP3K8) is a mitogen-activated protein kinase (MAPK) kinase kinase (MAP3K) that phosphorylates the MAPK kinases MEK1 and MEK2 (MEK1/2), which, in turn, activate the MAPKs extracellular signal-regulated kinase 1 (ERK1) and ERK2 (ERK1/2) in macrophages stimulated through the interleukin-1 receptor (IL-1R), Toll-like receptors (TLRs), or the tumor necrosis factor receptor (TNFR). We describe a conserved and critical role for TPL2 in mediating the effector functions of neutrophils through the activation of the p38 MAPK signaling pathway. Gene expression profiling and functional studies of neutrophils and monocytes revealed a MEK1/2-independent branch point downstream of TPL2 in neutrophils. Biochemical analyses identified the MAPK kinases MEK3 and MEK6 and the MAPKs p38α and p38δ as downstream effectors of TPL2 in these cells. Genetic ablation of the catalytic activity of TPL2 or therapeutic intervention with a TPL2-specific inhibitor reduced the production of inflammatory mediators by neutrophils in response to stimulation with the TLR4 agonist lipopolysaccharide (LPS) in vitro, as well as in rodent models of inflammatory disease. Together, these data suggest that TPL2 is a drug target that activates not only MEK1/2-dependent but also MEK3/6-dependent signaling to promote inflammatory responses.

Giardia duodenalis induces pathogenic dysbiosis of human intestinal microbiota biofilms

Giardia duodenalis is a prevalent cause of acute diarrheal disease worldwide. However, recent outbreaks in Italy and Norway have revealed a link between giardiasis and the subsequent development of chronic post-infectious irritable bowel syndrome. While the mechanisms underlying the causation of post-infectious irritable bowel syndrome remain obscure, recent findings suggest that alterations in gut microbiota communities are linked to the pathophysiology of irritable bowel syndrome. In the present study, we use a laboratory biofilm system to culture and enrich mucosal microbiota from human intestinal biopsies. Subsequently, we show that co-culture with Giardia induces disturbances in biofilm species composition and biofilm structure resulting in microbiota communities that are intrinsically dysbiotic - even after the clearance of Giardia. These microbiota abnormalities were mediated in part by secretory-excretory Giardia cysteine proteases. Using in vitro cell culture and germ-free murine infection models, we show that Giardia-induced disruptions of microbiota promote bacterial invasion, resulting in epithelial apoptosis, tight junctional disruption, and bacterial translocation across an intestinal epithelial barrier. Additionally, these dysbiotic microbiota communities resulted in increased activation of the Toll-like receptor 4 signalling pathway, and overproduction of the pro-inflammatory cytokine IL-1beta in humanized germ-free mice. Previous studies that have sought explanations and risk factors for the development of post-infectious irritable bowel syndrome have focused on features of enteropathogens and attributes of the infected host. We propose that polymicrobial interactions involving Giardia and gut microbiota may cause persistent dysbiosis, offering a new interpretation of the reasons why those afflicted with giardiasis are predisposed to gastrointestinal disorders post-infection.

Regulatory T-cell depletion in the gut caused by integrin β7 deficiency exacerbates DSS colitis by evoking aberrant innate immunity

Integrin α4β7 controls lymphocyte trafficking into the gut and has essential roles in inflammatory bowel disease (IBD). The α4β7-blocking antibody vedolizumab is approved for IBD treatment; however, high dose of vedolizumab aggravates colitis in a small percentage of patients. Herein, we show that integrin β7 deficiency results in colonic regulatory T (Treg) cell depletion and exacerbates dextran sulfate sodium (DSS) colitis by evoking aberrant innate immunity. In DSS-treated β7-deficient mice, the loss of colonic Treg cells induces excessive macrophage infiltration in the colon via upregulation of colonic epithelial intercellular adhesion molecule 1 and increases proinflammatory cytokine expression, thereby exacerbating DSS-induced colitis. Moreover, reconstitution of the colonic Treg cell population in β7-deficient mice suppresses aberrant innate immune response in the colon and attenuates DSS colitis. Thus, integrin α4β7 is essential for suppression of DSS colitis as it regulates the colonic Treg cell population and innate immunity.

Quality of methods reporting in animal models of colitis

BACKGROUND

Current understanding of the onset of inflammatory bowel diseases relies heavily on data derived from animal models of colitis. However, the omission of information concerning the method used makes the interpretation of studies difficult or impossible. We assessed the current quality of methods reporting in 4 animal models of colitis that are used to inform clinical research into inflammatory bowel disease: dextran sulfate sodium, interleukin-10, CD45RB T cell transfer, and 2,4,6-trinitrobenzene sulfonic acid (TNBS).

METHODS

We performed a systematic review based on PRISMA guidelines, using a PubMed search (2000-2014) to obtain publications that used a microarray to describe gene expression in colitic tissue. Methods reporting quality was scored against a checklist of essential and desirable criteria.

RESULTS

Fifty-eight articles were identified and included in this review (29 dextran sulfate sodium, 15 interleukin-10, 5 T cell transfer, and 16 TNBS; some articles use more than 1 colitis model). A mean of 81.7% (SD = ±7.038) of criteria were reported across all models. Only 1 of the 58 articles reported all essential criteria on our checklist. Animal age, gender, housing conditions, and mortality/morbidity were all poorly reported.

CONCLUSIONS

Failure to include all essential criteria is a cause for concern; this failure can have large impact on the quality and replicability of published colitis experiments. We recommend adoption of our checklist as a requirement for publication to improve the quality, comparability, and standardization of colitis studies and will make interpretation and translation of data to human disease more reliable.

Image Analysis-Based Approaches for Scoring Mouse Models of Colitis

Mouse models of inflammatory bowel disease are critical for basic and translational research that is advancing the understanding and treatment of this disease. Assessment of these mouse models frequently relies on histologic endpoints. In recent years, whole slide imaging and digital pathology-based image analysis platforms have become increasingly available for implementation into the pathology workflow. These automated image analysis approaches allow for nonbiased quantitative assessment of histologic endpoints. In this study, the authors sought to develop an image analysis workflow using a commercially available image analysis platform that requires minimal training in image analysis or programming, and this workflow was used to score 2 mouse models of colitis that are primarily characterized by immune cell infiltrates in the lamina propria. Although the software was unable to accurately and consistently segment hematoxylin and eosin–stained sections, automated quantification of CD3 immunolabeling resulted in strong correlations with the pathologist’s score in all studies and allowed for the identification of 8 of the 9 differences among treatment groups that were identified by the pathologist. These results demonstrate not only the ability to incorporate solutions based on image analysis into the pathologist’s workflow but also the importance of immunohistochemical or histochemical surrogates for the incorporation of image analysis in histologic assessments.

Claudin-3 and occludin tissue content in the glands of colonic mucosa with and without a fecal stream

The synthesis of the proteins of the apical tight junctions (TJs) depends on a continuous supply of short-chain fatty acids (SCFAs) in colonic epithelium. No studies have evaluated the tissue contents of the TJs proteins in colon segments devoid of a fecal stream. To evaluate the contents of claudin-3 and occludin in the glands of colonic mucosa devoid of a fecal stream. Forty-five rats underwent a diversion of the fecal stream via a left side colostomy and distal mucous fistula. Three groups of 15 animals each were sacrificed at 6, 12 or 18 weeks after surgery. The presence and severity of colitis were defined by histology and inflammation grading scales, respectively. The expression of claudin-3 and occludin were evaluated by immunohistochemistry, and their contents were evaluated by computer-assisted image analysis. Mann-Whitney and Kruskal-Wallis tests were used to evaluate the results at a significance level of 5% (p < 0.05). The colonic epithelium without a fecal stream had a higher degree of inflammation. Colonic glands without a fecal stream showed a reduction in claudin-3 content independent of the time and reduction in occludin content after 12 weeks of intestinal exclusion. The content of claudin-3 and occludin were mainly reduced at the apical surfaces of the colon glands, whereas segments retaining the fecal stream were maintained. The content of claudin-3 was not reduced with time, although the levels of occludin were reduced after 6 weeks and did not vary thereafter. Deficiencies in SCFAs decreased the content of claudin-3 and occludin in colonic glands with the areas of worst inflammation, confirming the importance of an adequate supply of SCFAs in maintaining the integrity of TJ proteins.

Murine Models of Inflammatory Bowel Disease (IBD)

Animal models of human disease are a critical tool in both basic research and drug development. The results of preclinical efficacy studies often inform progression of therapeutic candidates through the drug development pipeline; however, the extent to which results in inflammatory bowel disease (IBD) models predict human drug response is an ongoing concern. This review discusses how murine models are currently being used in IBD research. We focus on the considerations and caveats for commonly used models in preclinical efficacy studies and discuss the value of models that utilize specific pathogenic pathways of interest rather than model all aspects of human disease.

Whole-slide imaging and automated image analysis: considerations and opportunities in the practice of pathology

Digital pathology, the practice of pathology using digitized images of pathologic specimens, has been transformed in recent years by the development of whole-slide imaging systems, which allow for the evaluation and interpretation of digital images of entire histologic sections. Applications of whole-slide imaging include rapid transmission of pathologic data for consultations and collaborations, standardization and distribution of pathologic materials for education, tissue specimen archiving, and image analysis of histologic specimens. Histologic image analysis allows for the acquisition of objective measurements of histomorphologic, histochemical, and immunohistochemical properties of tissue sections, increasing both the quantity and quality of data obtained from histologic assessments. Currently, numerous histologic image analysis software solutions are commercially available. Choosing the appropriate solution is dependent on considerations of the investigative question, computer programming and image analysis expertise, and cost. However, all studies using histologic image analysis require careful consideration of preanalytical variables, such as tissue collection, fixation, and processing, and experimental design, including sample selection, controls, reference standards, and the variables being measured. The fields of digital pathology and histologic image analysis are continuing to evolve, and their potential impact on pathology is still growing. These methodologies will increasingly transform the practice of pathology, allowing it to mature toward a quantitative science. However, this maturation requires pathologists to be at the forefront of the process, ensuring their appropriate application and the validity of their results. Therefore, histologic image analysis and the field of pathology should co-evolve, creating a symbiotic relationship that results in high-quality reproducible, objective data.